Imagine I am 17. In order to become 18 I first need to become 17 and a half, I need to get halfway across the remaining age distance. Then I need to get halfway across the remaining distance again, so now I am 17 and 3 quarters. I can continue doing this to infinity, dividing the distance as I get close and closer to being 18, but I never actually reach 18 because there is an infinite number of halfway points between 17 and 18. We can thus conclude that it is impossible to come of age and that you can only infinitely approach it given infinite time.